1. Field of the Invention (Technical Field)
The present invention relates to a fluid transport lining system and more particularly to a variable Manning coefficient liner system, a gasket free liner adjoining system, system and a novel elbow system for changing the direction of the flow of liquids.
2. Background Art
Ditches formed in the earth for conveying water to a point or to an area of use have been common throughout the world for generations. Earthen ditches have been used to transport potable water, irrigation water, and other fluids and materials. Earthen irrigation ditches continue to be significant in the transportation of water because they are readily and inexpensively formed in almost any terrain.
The term “ditch” as used in this document means any excavation dug in the earth, or any structure partially or completely installed above earth, that may be referred to as a drain, channel, canal or acequia, whether lined or unlined, usually but not always relying primarily on gravity to transport fluids and materials along descending elevations.
During transportation of water through earthen ditches that are unlined by a material other than dirt (“unlined ditches”), significant quantities of that ever more precious commodity, water, are lost because of seepage, erosion, trans-evaporation, and other causes. Tests indicate that as much as 80-90% of water may be lost during transportation through an unlined earthen ditch before water is delivered to a point or area for application and use.
It should be appreciated that loss of water, referred to as “seepage loss,” may be considerable. At least one report issued by New Mexico State University entitled “Field/Laboratory Studies for the Fast Ditch Lining System,” dated Feb. 10, 2002, (“Report”) indicates the results of tests conducted over a nine day interval. Total water losses during the nine-day test period were estimated to be 14,245,010 gallons, or 85.8% of total flow, when water was conducted through an unlined earthen ditch. The Report attributes most water losses to existing vegetation overgrowth, tree root systems, gopher holes, evaporation, and seepage or percolation. On the other hand, that same report, based on field measurements taken with a liner system disclosed in at least one of the Fast Ditch Patents and Applications (a term defined below) that had been installed in the same earthen ditch showed a total loss of only 7.3% of total flow.
Unlined earthen ditches must be regularly maintained, cleaned, and repaired to avoid loss of water through wall collapse; accumulated debris, absorption through dirt walls, capillary action, and rodent activity, are among many causes of ditch deterioration. Because repair and maintenance of unlined ditches is costly and labor intensive, various methods for lining unlined ditches have been suggested. Those methods include use of concrete, metal, and polyvinyl chloride materials. Those suggestions; however, have proven inadequate for a number of reasons including at least cost and unresponsiveness to modern environmental concerns. Some materials, like concrete, are difficult to install in remote geographical areas, are inflexibly positioned once installed, and often require major construction efforts that are neither practical nor affordable based on cost-benefit analyses.
Exemplary solutions to problems associated with lining, both lined and unlined ditches, are provided in the following patents and patent applications by one or more of the inventors named in connection with this document: U.S. Pat. No. 6,273,640 issued Aug. 14, 2001; U.S. Pat. No. 6,692,186 issued Feb. 17, 2004; U.S. Pat. No. 6,722,818 issued Apr. 20, 2004; U.S. Pat. No. 7,025,532 issued Apr. 11, 2006; U.S. Pat. No. 7,165,914 issued Jan. 23, 2007; U.S. Pat. No. 7,156,580 issued Feb. 2, 2007; U.S. Pat. No. 7,357,600 issued Apr. 15, 2008; U.S. Pat. No. 7,470,085 issued Dec. 30, 2008; application Ser. No. 12/100,829 filed Apr. 10, 2008; and U.S. Pat. No. 8,439,602 issued May 14, 2013.
As can be seen, there are presently several lining systems in the prior art. However, the embodiments disclosed herein constitute significant and novel improvements over these prior art systems. The main purpose of the prior art patents was to provide for a light weight, flexible liner that could be installed with simple tools into an existing or newly excavated trench to provide a system that was water tight for applications in irrigation and storm water management. The original designs were to join multiple corrugations together to form straight sections that could be connected together with a nested connection utilizing a foam gasket or the like for flexibility to form a liquid transportation system.
Several iterations of the designs were implemented to improve flow characteristics, water tightness in the nested connection and flexibility. All the design changes were made to accommodate the thermo-forming manufacturing process.
The first consideration in the new design is to develop a system that can be manufactured utilizing the injection molding process. The second consideration is for an easy and stackable transport system for the molded sections. Finally, the molded sections must not include too many variable molded parts to keep down the complexity and expense of the system.
The injection molding process yields a product that has high tolerances, and therefore can achieve a watertight seal without the use of a foam or rubber gasket. Thermo-forming provides for low manufacturing tolerances that require additional elements or manipulation to prevent leakage.
Also, given the characteristics of the thermos-forming process, the draw depth of the tool yielded parts that were inconsistent in wall thickness leaving the corrugations thin and inconsistent in the valleys, rendering the overall part venerable to puncturing given live loading situations such as animals walking in the channel, installation in hot temperatures, and brittleness in cold temperatures.
The use of corrugations in the prior art and previous patents was solely for making the straight section flexible for subtle changes in direction during installation. The focus of the design was to ensure the corrugations were tali enough to provide flexibility without increasing the Manning's coefficient of friction. Once the design of the corrugation was constructed, the Manning's coefficient of friction was fixed for that specific corrugation design.